Wireless communication system, base station device, move control node, and method of wireless communication

ABSTRACT

A base station is provided. The base station includes a transmitter and a receiver. The transmitter transmits, to a node including mobility management function, a setup message, the message including both first information about a tracking area supported in the base station and second information indicating a type of the cell of the base station. The receiver receives a response message of the setup message from the node including mobility management function.

The present application is a Continuation Application of U.S.application Ser. No. 15/912,507 filed Mar. 5, 2018, which is aContinuation Application of U.S. application Ser. No. 15/419,980 filedJan. 30, 2017, which is a Continuation Application of U.S. applicationSer. No. 14/969,128 filed Dec. 15, 2015, which is a continuationapplication of U.S. patent application Ser. No. 12/865,190 filed on Jul.29, 2010, which is a National Stage Entry of international applicationPCT/JP2009/051578, filed on Jan. 30, 2009, which claims priority fromJapanese Patent Application No. 2008-021304 filed on Jan. 31, 2008, thedisclosures of each of which are incorporated by reference herein intheir entirely.

TECHNICAL FIELD

The present invention relates to a wireless communication system, a basestation, a mobility management node, and a wireless communicationmethod.

BACKGROUND ART

According to LTE (Long Term Evolution) that is being standardized in3GPP (3rd Creation Partnership Projects) at present, there has beenproposed a wireless communication system which includes EUTRAN (EvolvedUMTS Terrestrial Radio Access Network, UMTS=Universal MobileTelecommunication System) and EPC (Evolved Packet Core) that areconfigured as shown in FIG. 1 (4.2.1 of Non-patent document 1, FIGS.4.2.1-1 and 4.2.1-2 of Non-patent document 2). The above titles are notrestrictive, but EUTRAN may be called “LTE”, EPC may be called SAE(System Architecture Evolution), and EUTRAN and EPC may collectively becalled EPS (Evolved Packet System).

As shown in FIG. 1, the EUTRAN includes eNode B (evolved Node B) 10 as abase station. The EPC includes CN (Core Network) Nodes comprising MME(Mobility Management Entity) 20 as a mobility management node, S-GW(Serving Gateway) 30 as a gateway, P-GW (Packet Data Network Gateway) 40as a higher-level gateway, and HSS (Home Subscriber Server) 50. eNode 10is connected to UE (User Equipment) as a wireless communicationapparatus through a wireless interface.

MME 20 is a node having a mobility management (location registration)function for UE 60, a handover control function, a selection functionfor S-GW 30 and P-GW 40, a bearer management function, etc (4.4.2 ofNon-patent document 1). S-GW 30 is a node for transferring user-planepacket data between eNode B 10 and P-GW 40. P-GW 40 is a node fortransferring transmission packet data from its own network (Home PLMN,PLMN=Public Land Mobile Network) to an external network (Visit PLMN) andtransferring reception packet data from an external network to its ownnetwork. HSS 50 is a server for saving user information that is used toauthenticate UE 60.

According to LTE, TAs (Tracking areas) are assigned to UE 60 as areas inwhich UE 60 is to be paged when an incoming call is received (5.2.3 ofNon-patent document 1). Specifically, when UE 60 registers its locationin eNode B 10, TAs are assigned to UE 60 by MME 20, and the list ofassigned TAs is registered in UE 60. If UE 60 detects when it has movedto a TA that is not included in the registered list, UE 60 registers itslocation again in eNode B 10 in order to update the TAs (5.3.3.1 ofNon-patent document 1).

In a region where the paging traffic is high, the number of TAs that areassigned to UE 60 when UE 60 registers its location is reduced in orderto reduce the number of areas in which UE 60 is to be paged. In order toreduce the number of times that UE 60 registers its location, on theother hand, the number of TAs assigned to UE 60 which is moving at ahigh speed is increased.

Consequently, there is a trade-off between the number of TAs forreducing the paging traffic and the number of TAs for reducing thenumber of times that UE 60 registers its location. It is thus necessaryto optimize the number of TAs assigned to UE 60 in view of thetrade-off.

A general process of assigning TAs to UE 60 will be described below.

It is assumed that from among the respective cells of a plurality ofeNodes B 10, cells C#1 through C#23 are arranged as shown in FIG. 2, andcells C#1 through C#23 belong to TA#1 through TA#7 as follows:

TA#1=C#1, C#2, C#3, C#4, C#5

TA#2=C#17, C#18, C#19, C#20, C#21, C#22

TA#3=C#6, C#7, C#8

TA#4=C#9, C#10, C#12, C#13, C#14

TA#5=C#16

TA#6=C#11, C#15

TA#7=C#23

Generally, MME 20 assigns TAs to UE 60 according to a rule that ismanually established by the operator. According to the rule, a pluralityof TAs are fixedly assigned to UE 60.

Specifically, in the example shown in FIG. 2, the rule is such that whenUE 60 registers its location in either one of eNodes B 10 of the cellsbelonging to TA#1, two TAs represented as TA#1 and TA#4 are fixedlyassigned to UE 60.

Even when UE 60, which is moving at a high speed, registers its locationin either one of eNodes B 10 of the cells belonging to TA#1, TA#1 andTA#4 are assigned to UE 60.

If the cells belonging to TA#1 and TA#4 are of the type which covers avery small range (having a radius of several hundreds meters), forexample, then even though MME 20 assigns TA#1 and TA#4 to UE 60, sinceUE 60 travels through TA#1 and TA#4 and enters TA#5 in several seconds,UE 60 needs to newly register its location.

The time which UE 60 takes to travel through TA#1 and TA#4 will beactually calculated as described below.

It is assumed that UE 60 registers its location in eNode B 10 of C#2belonging to TA#1, the cells belonging to TA#1 and TA#4 have a diameterof 500 m (meter), and UE 60 travels at a speed of 80 km (kilo meter)/h(hour).

The distance over which UE 60 travels through TA#1 and TA#4 is 2500 m(meter) across five cells (C#2, C#3, C#5, C#12, C#13) (=500 m*5).

Therefore, the time which UE 60 takes to travel through TA#1 and TA#4 is113 seconds (≈2500 m/80 km/h). This numerical value indicates that UE 60will do its location registration in about two minutes. Therefore, thenumber of times that UE 60 registers its location cannot be reduced.

Since the number of times that UE 60 registers its location cannot bereduced, an optimum number of TAs cannot be assigned to UE 60.

According to the practice of fixedly assigning a plurality of TAs to UE60, a plurality of TAs are also assigned to UE 60 which mostly does notmove in daytime. Consequently, since the paging traffic for paging UE60, when an incoming call is received, has to cover the plural TAs, thepaging traffic cannot be reduced, resulting in a large burden imposed onthe wireless communication system.

As described above, the practice of fixedly assigning a plurality of TAsto UE 60 is problematic in that an optimum number of TAs cannot beassigned to UE 60.

Furthermore, in as much as the operator manually sets the rule forassigning TAs to UE 60 in MME 20, the rule has to be re-established eachtime eNode B 10 is added or removed. This requires the operator to spenda lot of time and make a lot of effort, and hence results in an increasein OPEX (Operation and Expenditure).

-   Non-patent document 1: 3GPP TS 23.401, V8.0.0-   Non-patent document 2: 3GPP TS 36.300, V8.2.0

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a wirelesscommunication system, a base station, a mobility management node, and awireless communication method which are capable of solving at least oneof the above problems.

A wireless communication system according the present inventioncomprises a base station and a mobility management node, wherein

said base station sends at least one information from among locationinformation of the base station and information about the size of a cellof the base station, to said mobility management node; and

said mobility management node receives at least one information fromamong the location information of the base station and the informationabout the size of the cell of the base station, from said base station.

A base station according to the present invention comprises atransmitter for sending at least one information from among locationinformation of a base station and information about the size of a cellof the base station, to a mobility management node.

A first mobility management node according to the present inventioncomprises a receiver for receiving at least one information from amonglocation information of a base station and information about the size ofa cell of the base station, from said base station.

A second mobility management node according to the present inventioncomprises:

a receiver for receiving, from a base station, information aboutmovement of a wireless communication apparatus which registers itslocation in said base station; and

a controller for assigning a tracking area based on information about alayout of said base station and the information about movement.

According to the present invention, a first wireless communicationmethod to be carried out by a base station, comprises:

the transmission step of sending at least one information from amonglocation information of the base station and information about the sizeof a cell of the base station, to a mobility management node.

According to the present invention, a second wireless communicationmethod to be carried out by a mobility management node comprises thereception step of receiving, from a base station, at least oneinformation from among location information of the base station andinformation about the size of a cell of the base station.

According to the present invention, the base station is arranged to sendat least one information from among the location information of the basestation and the information about the size of the cell of the basestation, to the mobility management node.

Therefore, since the mobility management node can recognize a layout ofcells by receiving at least one information from among the locationinformation of the base station and the information about the size ofthe cell thereof, the OPEX required by manual operation of the operatorfor assigning tracking areas can be reduced, and it is possible toassign an optimum number of tracking areas to the wireless communicationapparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the overall configuration of a wirelesscommunication system;

FIG. 2 is a diagram showing another example of a map representing thelayout of cells;

FIG. 3 is a block diagram showing the configuration of a wirelesscommunication system according to a first exemplary embodiment of thepresent invention;

FIG. 4 is a sequence diagram illustrating an operation of the wirelesscommunication system according to the first exemplary embodiment of thepresent invention;

FIG. 5 is a block diagram showing the configuration of a wirelesscommunication system according to a second exemplary embodiment of thepresent invention;

FIG. 6 is a sequence diagram illustrating an operation of the wirelesscommunication system according to the second exemplary embodiment of thepresent invention at the time eNode B is added;

FIG. 7 is a diagram showing an example of a map representing the layoutof cells;

FIG. 8 is a sequence diagram illustrating an operation of the wirelesscommunication system according to the second exemplary embodiment of thepresent invention at the time a range covered by the cell of eNode B ischanged;

FIG. 9 is a flowchart of an operation sequence of MME when it assignsTAs according to the second exemplary embodiment of the presentinvention;

FIG. 10 is a flowchart of a processing sequence for calculating a TArange in steps 706, 712 shown in FIG. 9;

FIG. 11 is a sequence diagram illustrating an operation of a wirelesscommunication system according to a third exemplary embodiment of thepresent invention at the time the UE is attached; and

FIG. 12 is a sequence diagram illustrating an operation of a wirelesscommunication system according to a fourth exemplary embodiment of thepresent invention at the time the UE registers its location.

BEST MODE FOR CARRYING OUT THE INVENTION

The best mode for carrying out the present invention will be describedbelow with reference to the drawings.

In all exemplary embodiments to be described below, the overallconfiguration of a wireless communication system is identical to theoverall configuration of the wireless communication system shown in FIG.1.

First Exemplary Embodiment

As shown in FIG. 3, eNode B 10 according to the present exemplaryembodiment includes transmitter 11 for transmitting location informationof the cell of eNode B 10 and information about the size thereof to MME20.

MME 20 according to the present exemplary embodiment includes receiver21 for receiving the location information of the cell of eNode B 10 andthe information about the size thereof from eNode B 10.

Operation of the present exemplary embodiment will be described belowwith reference to FIG. 4.

As shown in FIG. 4, in step 201, transmitter 11 of eNode B 10 sends thelocation information of the cell of eNode B 10 and the information aboutthe size thereof to MME 20. The information sent to MME 20 is receivedby receiver 21 of MME 20.

Since MME 20 can recognize the layout of cells by receiving the locationinformation of the cell of eNode B 10 and the information about the sizethereof, the OPEX required by manual operation of the operator forassigning TAs can be reduced, and it is possible to assign an optimumnumber of TAs to UE 60.

Second Exemplary Embodiment

As shown in FIG. 5, eNode B 10 according to the present exemplaryembodiment is different from eNode B 10 according to the first exemplaryembodiment shown in FIG. 3 in that receiver 12 and controller 13 areadded thereto.

Controller 13 includes information about eNode B 10, described below, ina message.

(1) Location Information of the Cell of eNode B 10:

For example, the location information of the cell is the information oflatitude and longitude of the location of the cell of eNode B 10 (e.g.,the central location of the cell or the central location of eNode B 10),which is acquired by a location information measuring device on eNode B10 using a GPS (Global Positioning System) or the like. The locationinformation of the cell may be information required to calculate thelocation, which is acquired by eNode B 10 using the GPS or the like.

(2) Information about the Size of the Cell of eNode B 10:

For example, the size of the cell may represent the diameter or radiusof the cell (e.g., 500 m, 1 km, or 2 km). Alternatively, the size of thecell may represent a type indicative of the size of the cell (e.g.,Macro, Micro, Pico, or Femto).

(3) TA to which the Cell of eNode B 10 Belongs:

(4) The eNode B 10 Number or the Cell Number of eNode B 10:

The information (2) through (4) is preset in eNode B 10.

The transmitter 11 sends a message including information (1) through (4)with respect to eNode B 10 to MME 20.

Receiver 12 receives a message including the information of TAs assignedto UE 60 which has registered its location in its own eNode B 10, fromMME 20.

Messages are also sent to and received from UE 60 by transmitter 11,receiver 12, and controller 13.

MME 20 according to the present exemplary embodiment is different fromMME 20 according to the first exemplary embodiment shown in FIG. 3 inthat transmitter 22 and controller 23 are added thereto.

Receiver 21 receives the message including the information (1) through(4) with respect to eNode B 10 from eNode B 10.

Controller 23 creates a map representative of the layout of cells basedon the information (1) through (4) with respect to eNode B 10.

Controller 23 dynamically assigns an optimum number of TAs to UE 60which has registered its location in eNode B 10, based on the movingspeed and moving direction of UE 60 and the map, and includes theinformation of the assigned TAs in a message.

Transmitter 22 sends the message including the information of the TAsassigned to UE 60 which has registered its location in eNode B 10, toeNode B 10.

Messages are also sent to and received from S-GW 30 by transmitter 22,receiver 21, and controller 23.

Operation of the present exemplary embodiment will be described below.

In order for the wireless communication system to provide communicationservices stably and optimally, it adds, removes, and redeploys eNode B10 depending on the traffic volume in a certain region and the placesuch as between buildings where a wireless signal from existing eNode B10 does not reach.

[When eNode B 10 is Added]

Operation at the time eNode B 10 is added will be described withreference to FIG. 6.

It is assumed that, as shown in FIG. 7, C#30 belonging to TA#1 is newlyadded to the cell layout shown in FIG. 2.

As shown in FIG. 6, eNode B 10 of C#30 added to TA#1 is newly added instep 401.

In step 402, transmitter 11 of added eNode B 10 sends a setup message(S1 setup message) including the information (1) through (4) withrespect to eNode B 10 to MME 20.

Then, in step 403, controller 23 of MME 20 calculates the range of TA#3based on the location information of C#1 through C#5, C#30 belonging toTA#1, creates a new map as shown in FIG. 7, and stores the new map in amemory (not shown in any of the figures).

Thereafter, in step 404, transmitter 22 of MME 20 sends a responsemessage to the setup message (S1 Setup Response message) to eNode B 10.

[When eNode B 10 is Removed]

When eNode B 10 is removed, the cell of removed eNode B 10 is deleted.Therefore, MME 20 cannot receive a notice from removed eNode B 10.However, when eNode B 10 is removed, the connection link between removedeNode B 10 and MME 20 is cut off.

Controller 23 of MME 20 judges eNode B 10 whose connection link to itsown MME 20 has been cut off as being removed, deletes the cell ofremoved eNode B 10 from the map, creates a new map, and stores the newmap in the memory (not shown in any of the figures).

[When the Range Covered by the Cell of eNode B 10 is Changed]

Operation at the time the range covered by the cell of eNode B 10 ischanged will be described below with reference to FIG. 8.

As shown in FIG. 8, in step 601, the range covered by the cell of eNodeB 10 is changed because of a redeployment or configurational change(replacement of the antenna, a change in the antenna direction, etc.) ofeNode B 10.

In step 602, transmitter 11 of eNode B 10 with the cell-covered rangebeing changed sends a reconfiguration message (S1 Reconfigurationmessage) including information (1) through (4) with respect to eNode B10 to MME 20.

Then, in step 603, controller 23 of MME 20 calculates the range of theTA, to which the cell with the range covered thereby being changedbelongs, creates a new map, and stores the new map in the memory (notshown in any of the figures).

Thereafter, in step 604, transmitter 22 of MME 20 sends a responsemessage (S1 Reconfiguration Response message) to the reconfiguration toeNode B 10.

[When the Location of UE 60 is Registered]

When the location of UE 60 is registered (TA Update), controller 23 ofMME 20 assigns an optimum number of TAs to UE 60 based on the movingspeed Sue and moving direction Dir of UE 60.

(A) Calculation of the Moving Speed Sue of UE 60:

For example, the moving speed Sue of UE 60 can be calculated from achange in the number of TAs assigned when the location of UE 60 isregistered within a certain period. Specifically, if the number of TAshas increased, then the moving speed of UE 60 is judged as high.Conversely, if the number of TAs has decreased, then the moving speed ofUE 60 is judged as low. Information of the moving speed of UE 60 mayacquired by other methods. For example, MME 20 can receive theinformation of the moving speed which is recognized by UE 60 from UE 60via eNode B 10.

(B) Calculation of the Moving Direction Dir of UE 60:

For example, the moving direction Dir of UE 60 can be calculated fromthe track of registered locations of UE 60 within a certain period.Information of the moving direction Dir of UE 60 may acquired by othermethods. For example, MME 20 can receive the information of the movingdirection which is recognized by UE 60 from UE 60 via eNode B 10.

(C) Assignment of TAs to UE 60:

When TAs are assigned to UE 60, they are assigned such that it takes UE60 six minutes or more, for example, to travel through all the assignedTAs. The time that UE 60 takes to travel through all the assigned TAs isnot limited to six minutes, but may be determined appropriatelydepending on the design of the system.

Specific Example 1

It is assumed that, as shown in FIG. 7, UE 60 registers its location ineNode B 10 of C#2 belonging to TA#1, the cells belonging to TA#1 andTA#4 have a diameter of 2 km. UE 60 has a moving speed Sue of 80 km/h,and UE 60 has a moving direction Dir from TA#1 to TA#4.

If two TA#1 and TA#4 are assigned to UE 60, then the distance over whichUE 60 travels through TA#1 and TA#4 is 10 km across five cells (C#2,C#3, C#5, C#12, C#13) (=2 km*5). Therefore, the time which UE 60 takesto travel through TA#1 and TA#4 is 7.5 minutes (≈10 km/80 km/h). Sinceit takes UE 60 six minutes or more to travel through TA#1 and TA#4, twoTA#1 and TA#4 are assigned to UE 60.

Specific Example 2

It is assumed that, as shown in FIG. 7, UE 60 registers its location ineNode B 10 of C#2 belonging to TA#1, the cells belonging to TA#1 andTA#4 have a diameter of 1.5 km, UE 60 has a moving speed Sue of 80 km/h,and UE 60 has a moving direction Dir from TA#1 to TA#4.

If two TA#1 and TA#4 are assigned to UE 60, then the distance over whichUE 60 travels through TA#1 and TA#4 is 7.5 km across five cells (C#2,C#3, C#5, C#12, C#13) (=1.5 km*5). Therefore, the time which UE 60 takesto travel through TA#1 and TA#4 is 5.6 minutes (≈7.5 km/80 km/h). Itdoes not take UE 60 six minutes or more to travel through TA#1 and TA#4.

If three TA#1, TA#4, and TA#5 are assigned to UE 60 and the distance andthe time are recalculated, then the time which UE 60 takes to travelthrough TA#1. TA#4, and TA#5 is 6.8 minutes (≈9.0 km/80 km/h). Since ittakes UE 60 six minutes or more to travel through TA#1, TA#4, and TA#5,three TA#1, TA#4, and TA#5 are assigned to UE 60.

Specific Example 3

It is assumed that UE 60 registers its location in eNode B 10 of C#2belonging to TA#1, as is the case with the above examples, but UE 60 hasa moving speed Sue of 0 km/h.

It may be considered that UE 60 is in a company or the like and mostlydoes not move in daytime. Therefore, only one TA#1, to which C#2 ofeNode B 10, in which UE 60 has registered its location belongs, isassigned to UE 60. As only one TA is assigned to UE 60 that mostly doesnot move in daytime, the paging traffic for paging UE 60, when anincoming call is received, covers only TA#1, the paging traffic isreduced and no burden is imposed on the wireless communication system.

The above process of assigning TAs to UE 60 is described below.

As shown in FIG. 9, when UE 60 registers its location in eNode B 10,controller 23 of MME 20 calculates a moving speed Sue of UE 60 in step701. If the moving speed Sue is 0 in step 702, then controller 23assigns one TA, to which the cell of eNode B 10, in which UE 60 hasregistered its location, belongs to UE 60 in step 703.

If the moving speed Sue is not 0 in step 702, then controller 23calculates a moving direction Dir of UE 60 in step 704, and thencalculates a range of present TA (TA to which the cell of eNode B 10, inwhich UE 60 has registered its location, belongs) in step 705.

In the above exemplary embodiment, the range of TA is calculated if themoving speed Sue is not 0. However, the range of TA may be calculated ifthe moving speed Sue is equal to or higher than a predetermined speed,not 0.

The range of TA is calculated as shown in FIG. 10.

As shown in FIG. 10, the controller 23 sets, as x, the number of cells,of the cells belonging to TA, that are arrayed along the movingdirection Dir of UE 60 in step 801.

Then, controller 23 sets, as n, a next cell number (a first cell numberwhen control comes from step 801) in step 802, and then sets, as Dn, thediameter of cell n set in step 802 in step 803. At this time, thediameter of the cell received as the information in above (2) from eNodeB 10 is used as the diameter of cell n. If the information in above (2)received from eNode B 10 represents the radius or type of the cell, thenthe diameter of the cell is determined based on the receivedinformation.

Then, controller 23 sets the sum of present TAd (0 when control comesfrom step 801) and Dn set in step 803 as TAd representative of the rangecovered by TA, in step 804.

Then, controller 23 sets, as new x, the difference produced bysubtracting 1 from the present x in step 805. If x is 0 in step 806,then controller 23 stores TAd set in step 804 in the memory (not shownin any of the figures) in step 807.

If x is not 0 in step 806, then control goes back to step 802, and thesame processing is repeated until x becomes 0.

Therefore, the range TAd covered by TA is expressed by the equation 1below where n represents the cell number.

$\begin{matrix}{{TAd} = {\sum\limits_{1}^{n}{Dn}}} & {{Equation}\mspace{14mu}\lbrack 1\rbrack}\end{matrix}$

Referring back to FIG. 9, controller 23 sets, as TAd, the present rangeof TA calculated in step 705, and also sets, as TAdm, an initial value 0in step 706. Controller 23 then sets the sum of TAd and TAdm set in step706 as new TAd in step 707.

Then, in step 708, controller 23 determines travel time T which UE 60takes to travel through TA by dividing TAd newly set in step 707 bymoving speed Sue calculated in step 701.

Therefore, travel time T of UE 60 is expressed by equation 2 below wherem represents the TA number.

$\begin{matrix}{T = {\lbrack {\sum\limits_{1}^{m}{{TAd}(m)}} \rbrack \div {Sue}}} & {{Equation}\mspace{14mu}\lbrack 2\rbrack}\end{matrix}$

Then, if travel time T calculated in step 708 exceeds a predeterminedtime of X minutes (a time required for UE 60 to travel through all theassigned TAs) in step 709, then controller 23 assigns the present TAs toUE 60 in step 710.

If travel time T calculated in step 708 is equal to or shorter than theX minutes in step 709, then controller 23 sets, as new TAdm, TAd(m+1)representing a range covered by next TA along the moving direction of UE60 in step 711. Then, in step 712, controller 23 calculates TAdm newlyset in step 711. Control then goes back to step 707, and the sameprocessing is repeated until travel time T exceeds the X minutes.

In the present exemplary embodiment described above, the moving speedSue and the moving direction Dir are used as the information withrespect to the movement of UE 60. However, either the moving speed Sueor the moving direction Dir may be used in the present invention. Forexample, if only the moving speed Sue is used, then TAs that are presentaround the location of UE 60 may be assigned. If only the movingdirection Dir is used, then a given number TAs along that direction maybe assigned.

According to the present exemplary embodiment, as described above, wheneNode B 10 is added or when the range that is covered by the cell ischanged, eNode B 10 sends a message including the location informationof the cell of its own and the information about the size thereof to MME20.

Therefore, MME 20 can recognize the layout of cells based on thelocation information of the cell of eNode B 10 and the information aboutthe size thereof, and hence can dynamically assign an optimum number ofTAs to UE 60, as is the case with the first exemplary embodiment.

Furthermore, MME 20 is also capable of assigning an optimum number ofTAs, which make the number of location registrations of UE 60 and thenumber of paging events balanced, to UE 60 in view of the moving speedSue and the moving direction Dir of UE 60.

When eNode B 10 is removed, MME 20 can judge that eNode 10 is removedbased on the cut-off of the connection link to eNode B 10.

According to the present exemplary embodiment, since eNode B 10 sendsthe above information to MME 20, the manual operation of the operatorfor assigning TAs can be reduced and hence the OPEX can be reduced.

According to the present exemplary embodiment, when UE 60 registers itslocation, since MME assigns TAs to the UE based on the information aboutthe layout of eNodes B 10 and the information about the movement of theUE, optimum TAs can dynamically be assigned to the UE depending on themovement of the UE. The movement of the UE may be represented by themoving speed and the moving direction, for example.

Third Exemplary Embodiment

eNode B 10 according to the present exemplary embodiment is identical inconfiguration to, but is different in operation from, eNode B 10according to the second exemplary embodiment shown in FIG. 5.

According to the first exemplary embodiment, eNode B 10 sendsinformation (1) through (4) with respect to eNode B 10 to MME 20 wheneNode B 10 itself is added. According to the present exemplaryembodiment, eNode B 10 sends the information when UE 60 attaches itself.Attaching of UE 60 means first access from UE 60 to eNode B 10. e.g.,first access after the power supply is turned on. Other details ofoperation of eNode B 10 are the same as with the second exemplaryembodiment.

MME 20 according to the present exemplary embodiment is identical inconfiguration and operation to MME 20 according to second exemplaryembodiment shown in FIG. 5.

Operation of the present exemplary embodiment will be described belowwith reference to FIG. 11.

As shown in FIG. 11. UE 60 sends a message (Attach Request message)requesting its attachment to eNode B 10 in step 901.

In step 902, transmitter 11 of eNode B 10 as an attachment destinationsends a message (Initial UE Message) for starting an attach procedure,including information (1) through (4) with respect to eNode B 10 andinformation of the Attach Request message, to MME 20.

Then, if an authentication device (not shown in any of the figures) ofMME 20 successfully authenticates UE 60 using user information stored inHSS 50 in step 903, then transmitter 22 of MME 20 sends a message(Create Default Bearer Request message) requesting the creation of abearer to S-GW 30 in step 904.

In step 905, S-GW 30 sends the message (Create Default Bearer Requestmessage) requesting the creation of a bearer to P-GW 40. In steps 906,907, P-GW 40 sends a response message (Create Default Bearer Responsemessage) to the message requesting the creation of a bearer via S-GW 30to MME 20.

At this time, controller 23 of MME 20 performs a process of calculatinga range of TAs, to which the cell of eNode B 10 as the attachmentdestination belongs, creating a new map, and storing the new map in thememory, and also a process of assigning TAs to UE 60 which has attacheditself.

Then, in step 908, transmitter 22 of MME 20 sends a message (InitialContext Setup Request message) including the information of TAs assignedto UE 60 and a message (Attach Accept message) accepting the attachment,to eNode B 10. In step 909, transmitter 11 of eNode B 10 sends a message(Radio Bearer Establishment Request message) including the informationof TAs assigned to UE 60 and the message (Attach Accept message)accepting the attachment, to UE 60.

Thereafter, in step 910, UE 60 sends a message (Radio BearerEstablishment Response message) including a response message (AttachComplete message) to the message accepting the attachment, to eNode B10. Then, in step 911, transmitter 11 of eNode B 10 sends a message(Initial Context Setup Response message) including the response message(Attach Complete message) to the message accepting the attachment, toMME 20.

According to the present exemplary embodiment, as described above, whenUE 60 attaches itself, eNode B 10 sends information (1) through (4) withrespect to eNode B 10 to MME 20. Therefore, the latest information abouteNode B 10 can be indicated to MME 20. Other advantages are the same asthose of the second exemplary embodiment.

Fourth Exemplary Embodiment

eNode B 10 according to the present exemplary embodiment is identical inconfiguration to, but is different in operation from, eNode B 10according to the second exemplary embodiment shown in FIG. 5.

According to the first embodiment, eNode B 10 sends information (1)through (4) with respect to eNode B 10 to MME 20 when eNode B 10 itselfis added. According to the present exemplary embodiment, eNode B 10sends the information when UE 60 registers its location. Other detailsof the operation of eNode B 10 are the same as with the second exemplaryembodiment.

MME 20 according to the present exemplary embodiment is identical inconfiguration and operation to MME 20 according to second exemplaryembodiment shown in FIG. 5.

Operation of the present exemplary embodiment will be described belowwith reference to FIG. 12.

In FIG. 12, existing MME 20 and S-GW 30 are referred to as Old MME 20-Oand Old S-GW 30-O, respectively, MME 20 which eNode B 10 has newlyselected based on the information included in a location registrationrequest message (TAU Request message) from UE 60 is referred to as NewMME 20-N. and S-GW 30 which New MME 20-N has newly selected based on theinformation included in the TAU Request message is referred to as NewS-GW 30-N.

As shown in FIG. 12, UE 60 sends a TAU Request message for locationregistration to eNode B 10 in step 1001.

In step 1002, transmitter 11 of eNode B 10 as a location registrationdestination sends a message (Initial UE Message) for starting a TAUpdate procedure, including information (1) through (4) with respect toeNode B 10 and information of the TAU Request message, to New MME 20-N.

In step 1003, transmitter 22 of New MME 20-N sends a message (ContextRequest message) requesting context information of UE 60 to Old MME20-O. In step 1004, transmitter 22 of Old MME 20-O sends a responsemessage (Context Response message) to the message requesting contextinformation of UE 60 to New MME 20-N.

If the authentication device (not shown in any of the figures) of MME 20successfully authenticates UE 60 using user information stored in HSS 50in step 1005, then transmitter 22 of new MME 20-N sends a messageindicating that the context of UE 60 is validated for New MME 20-N andinvalidated for Old MME 20-O to Old MME 20-O in step 1006, and sends amessage (Create Default Bearer Request message) requesting the creationof a bearer to New S-GW 30-N in step 1007.

In step 1008, New S-GW 30-N sends a request message (Update BearerRequest message) for changing a data transfer route from Old S-GW 30-Oto New S-GW 30-N to P-GW 40. In step 1009, P-GW 40 sends a message(Update Bearer Response message) in response to the request message forchanging the data transfer route to New S-GW 30-N. In step 1010, NewS-GW 30-N sends a response message (Create Bearer Response message) tothe message for requesting the creation of a bearer to New MME 20-N. Instep 1011, a process of releasing the bearer with respect to Old S-GW30-O is carried out.

At this time, controller 23 of New MME 20-N performs a process ofcalculating a range of TAs, to which the cell of eNode B 10 as thelocation registration destination belongs, creating a new map, a processof storing the new map in the memory, and also a process of assigningTAs to UE 60 which has registered its location.

In step 1012, transmitter 22 of new MME 20-N sends a message (InitialContext Setup Request message) including the information of TAs assignedto UE 60 and a message (TAU Accept message) accepting the locationregistration, to eNode B 10. In step 1013, transmitter 11 of eNode B 10sends a message (Radio Bearer Establishment Request message) includingthe information of TAs assigned to UE 60 and the message accepting thelocation registration, to UE 60.

Thereafter, in step 1014, UE 60 sends a message (Radio BearerEstablishment Response message) including a response message (TAUComplete message) to the message accepting the location registration, toeNode B 10. Then, in step 1015, transmitter 11 of eNode B 10 sends amessage (Initial Context Setup Response message) including the responsemessage (TAU Complete message) to the message accepting the locationregistration, to MME 20.

According to the present exemplary embodiment, as described above, whenUE 60 registers its location, eNode B 10 sends information (1) through(4) with respect to eNode B 10 to MME 20. Therefore, the latestinformation about eNode B 10 can be indicated to MME 20. Otheradvantages are the same as those of the second exemplary embodiment.

The present invention has been described above in reference to theexemplary embodiments. However, the present invention is not limited tothe above exemplary embodiments. Rather, various changes that can beunderstood by those skilled in the art within the scope of the inventionmay be made to the arrangements and details of the present invention.

For example, in the above exemplary embodiments, the LTE wirelesscommunication system has been illustrated. However, the presentinvention is not limited to the LTE wireless communication system, butis also applicable to other wireless communication systems havingmobility management nodes, a base station, and a wireless communicationapparatus.

Furthermore, the above exemplary embodiments explain the wirelesscommunication system wherein the mobility management nodes and thegateway are separate from each other. However, the present invention isalso applicable to wireless communication systems wherein the mobilitymanagement nodes and the gateway are integral with each other.

What is claimed is:
 1. A base station comprising at least one processorconfigured to operate as: a receiver configured to receive an attachrequest message from a wireless communication apparatus; and atransmitter configured to send, to a mobility management entity, a firstmessage including both first information indicating a location of thebase station and second information indicating whether or not a type ofthe cell of the base station is a macro cell, if the base stationreceives the attach request message.
 2. The base station according toclaim 1, wherein the type of the cell of the base station is a typerepresentative of a size of the cell.
 3. The base station according toclaim 1, wherein the second information indicates that the type of thecell of the base station is a macro cell or a femto cell.
 4. The basestation according to claim 1, wherein the first message is a UE initialmessage.
 5. The base station according to claim 1, wherein the receiverreceives a second message, from the mobility management entity,including third information of a tracking area to which the wirelesscommunication apparatus is registered, and the transmitter transmits thesecond message to the wireless communication apparatus.
 6. The basestation according to claim 5, wherein the second message is an attachaccept message.
 7. A method by a base station comprising: receiving anattach request message from a wireless communication apparatus; andsending, to a mobility management entity, a first message including bothfirst information indicating a location of the base station and secondinformation indicating whether or not a type of the cell of the basestation is a macro cell, if the base station receives the attach requestmessage.
 8. The method according to claim 7, wherein the type of thecell of the base station is a type representative of a size of the cell.9. The method according to claim 7, wherein the second informationindicates that the type of the cell of the base station is a macro cellor a femto cell.
 10. The method according to claim 7, wherein the firstmessage is a UE initial message.
 11. The method according to claim 7,further comprising: receiving a second message, from the mobilitymanagement entity, including third information of a tracking area towhich the wireless communication apparatus is registered; andtransmitting the second message to the wireless communication apparatus.12. The method according to claim 11, wherein the second message is anattach accept message.